Quarterly report pursuant to Section 13 or 15(d)

Summary of Restricted Stock Activity (Detail)

v3.8.0.1
Summary of Restricted Stock Activity (Detail) - Restricted Stock
9 Months Ended
Sep. 30, 2017
$ / shares
shares
Shares of Restricted Stock  
Shares of Restricted Stock, Beginning balance | shares 606,618
Shares of Restricted Stock, Granted | shares 237,933
Shares of Restricted Stock, Vested | shares (192,152)
Shares of Restricted Stock, Forfeited | shares (9,550)
Shares of Restricted Stock, Ending balance | shares 642,849
Shares of Restricted Stock, Unvested restricted stock | shares 642,849
Weighted Average Grant Date Fair Value  
Weighted Average Grant Date Fair Value Outstanding, Beginning | $ / shares $ 33.51
Weighted Average Grant Date Fair Value, Granted | $ / shares 41.94
Weighted Average Grant Date Fair Value, Vested | $ / shares 36.26
Weighted Average Grant Date Fair Value, Forfeited | $ / shares 33.00
Weighted Average Grant Date Fair Value Outstanding, Ending | $ / shares 35.82
Weighted Average Grant Date Fair Value, Unvested restricted stock | $ / shares $ 35.82